Vertical antenna



Aug. 29, 1939. w. BERNDT 2,170,849

VERTI CAL ANTENNA Filed July 24, 1937 INVENTOR W41. 75/? BERN!) 7 BY gm, 1%

ATTORNEY Patented Aug. 29, 1939 UNITED STATES VERTICAL ANTENNA Walter Berndt, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphie m. b. IL, Berlin, Germany, a corporation of Germany Application July 24, 1937, Serial No. 155,446 In Germany August 1, 1936 4 Claims.

The invention is concerned with a vertical antenna for signal transmission which has a length greater than one-quarter wave and which is characterized by a perfectly sinuous distribution of the current.

It is known that vertical antennae exhibit purely sinuous current distribution only when their characteristic impedance is constant throughout their length. However, this condition will be fulfilled only when the cross-section of the antenna grows with its height. A vertical antenna having a constant characteristic impedance, therefore, is roughly formed by a cone with its apex pointing downwards. However, such a structure and 5 configuration involves serious mechanical drawbacks, and is difficult to make.

According to the present invention, the vertical antenna comprises two or more superposed cone structures, the apices of the latter all pointing downwards. The distribution of the current for each cone is purely sinuous. But also the distribution of the current over the entire antenna length is sinuous provided that the junction point between two cone members is located at a current loop (anti-node).

Figs. 1, 2, 2a and 4 illustrate different embodiments of the invention. Fig. 3 illustrates the current distribution of the antenna of Fig. 4.

In Fig. l is illustrated a vertical antenna according to the invention. The height of the antenna is equal to It consists of two metallic cones l, I, each of like size. The joint between the cones is here located in a current loop. The distribution of the current will thus be purely sinuous throughout the entire height of the antenna. The arrangement is substantially simpler to make than a cone having a height equal to onehalf wave.

Where the dimensions are large, the cones could (in practice) preferably consist of iron lattice masts or girders. An embodiment of this kind is shown in Fig. 2. The base or bottom .end consists of a conical iron girder i. The top part of the antenna consists of a plurality of wires 2, 2, 2 and 2", of dissimilar cross-section, which can be held in position within a wooden tower T. This embodiment shows that the term cone, as here used, does not imply only cones in the mathematical sense. It also includes conductors whose cross-section varies throughout their length. This change may be either steady and continuous, or may be discontinuous, i. e., in small steps or stages.

Instead of a girder part at the base end of the 55 antenna (Fig. 2), both the bottom and the top ends could comprise conductors of different crosssection. Such an arrangement is shown in Fig. 2a.

One distinct advantage inherent in the use of cone or pyramidal antennae, as here disclosed, is that it is feasible to reduce the aggregate height 5 of the antenna. For instance, if the distribution of the current is to be such that there is. a node a little distance above ground (Fig. 3), then the height of the aerial may be less if the joint between the cone members is located below the m current loop. For example, Fig. 4 shows an antenna of this sort. Here the distribution of cur rent is as shown in Fig. 3. To further reduce the construction height, a roof capacity C and a coil L are provided, as known in the art. The 13 coil is. included in the upper wire pyramid. To obtain a current node a little distance above ground, the total height of the aerial needs to be roughly one-third A; the proper dimensions having been chosen. 20

At the junction between the two pyramids, an insulator may be inserted. The latter may be bridged by a switch or a metallic clip.

What is claimed is:

1. A vertical antenna having a physical height 95 substantially less than a half the length of the operating wave consisting of a plurality of substantially pyramidal members each having a substantially constant characteristic impedance vertically arranged in an end to end series relan tionship, the apices of said members pointing downwards, the upper of said members having an electrical length greater than a quarter of the length of the operating wave, said antenna being so energized that a current loop appears in said upper member and a current node appears in said lower section above its lower end.

2. A vertical antenna having a physical height substantially less than a half the length of the operating wave consisting of a plurality of substantially pyramidal members each having a substantially constant characteristic impedance vertically arranged in an end to end series relationship, the apices of said members pointing downwards, the upper of said members having an electrical length greater than a quarter of the length of the operating wave, said antenna being so energized that a current loop appears in said upper member and a current node appears in said lower section above its lower end, the lowermost 50 of said pyramidal members consisting of a latticework metallic mast.

3. A vertical antenna having a physical height substantially less than a half the length of the operating wave consisting of a plurality of substantially pyramidal members each having a substantially constant characteristic impedance vertically arranged in an end to end series relationship, the apices of said members pointing downwards, the upper of said members having an electrical length greater than a quarter of the length of the operating Wave, said antenna being so energized that a current loop appears in said upper member and a current node appears in said lower section above its lower end, each of said pyramidal members consisting of a latticework metallic mast.

4. A vertical antenna having a physical height substantially less than a half the length of the operating wave consisting of a plurality of substantially pyramidal members each having a substantially constant characteristic impedance vertically arranged in an end to end series relationship, the apices of said members pointing downwards, the upper of said members having an electrical length greater than a quarter of the length of the operating wave, said antenna being so energized that a current loop appears in said upper member and a current node appears in said lower section above its lower end, the upper of said pyramidal members being formed of several serially connected wires of different cross-section which are suspended inside a non-conducting framework.

WALTER BERNDT. 

